#include<iostream>
#include<string>
using namespace std;
typedef long long LL;
const int N = 100;
LL f[N];
LL s[N];
int l, r;
int main()
{
	f[1] = 1;
	f[2] = 1;
	s[1] = 1;
	s[2] = 2;
	for (int i = 3; i < N; i++) {
		f[i] = f[i - 1] + f[i - 2];
		s[i] = s[i - 1] + f[i];
	}
	while (cin >> l >> r) {
		cout << s[r] - s[l - 1] << endl;
	}
	return 0;
}